Redox water treatment system

Abstract

An apparatus for treating a flow of water containing contaminants includes first and second permeable electrodes and a power supply is coupled to each of the first and second permeable electrodes to create an electrical potential therebetween. The first and second permeable electrodes are disposed within the flow of water containing contaminants with the first permeable electrode upstream from the second permeable electrode and the water containing contaminants flowing through and between the permeable electrodes. The permeable electrodes are spaced a select distance to promote an electric current in the water containing contaminants between the electrodes sufficient to sustain oxidation or reduction of the contaminants in the vicinity of the electrodes. The electrodes are preferably substantially planar plates disposed in parallel and substantially normal to the direction of water flow. The distance between the plates is between about 0.001 and 1 meter. The electrodes are preferably made of a conductive material selected from the group including carbon black, vitreous carbon, graphite, stainless steel, aluminum, copper, gold and gold plated stainless steel.

What is claimed is:  
     
       1. An apparatus for treating an in situ flow of ground water containing contaminants, the apparatus comprising: 
       first and second permeable metal electrodes, wherein one of said first and second permeable electrodes is a positive electrode and the other is a negative electrode; and  
       a power supply coupled to each of the first and second permeable electrodes to create an electrical potential therebetween,  
       the first and second permeable electrodes being disposed in situ within the flow of ground water containing contaminants with the first permeable electrode upstream from the second permeable electrode and the water containing contaminants flowing through and between the permeable electrodes, the permeable electrodes being spaced a select distance to promote an electric current in the water containing contaminants between the electrodes sufficient to sustain oxidation or reduction of The contaminants in the vicinity of the electrodes, whereby oxidation of the contaminates occurs in the vicinity of the positive electrode and reduction of the contaminants occurs in the vicinity of the negative electrode; wherein said flow of water is equal to a rate of flow of the groundwater.  
     
     
       2. The apparatus of  claim 1  wherein the electrodes comprise substantially planar plates disposed in parallel and substantially normal to the direction of flow. 
     
     
       3. The apparatus of  claim 2  further comprising a non-conductive spacer between the electrodes to maintain the select distance. 
     
     
       4. The apparatus of  claim 1  wherein the select distance is between about 0.001 and 1 meter. 
     
     
       5. The apparatus of  claim 1  wherein the electrodes are made of a conductive material selected from the group consisting of stainless steel, aluminum, copper, platinized titanium, mixed metal oxides, gold and gold plated stainless steel. 
     
     
       6. The apparatus of  claim 5  wherein the electrodes are in a form selected from the group consisting of perforated plates, screens, wool, felt and weave. 
     
     
       7. The apparatus of  claim 1  comprising more than one pair of first and second permeable electrodes disposed in series, with each of first and second permeable electrodes coupled to the power supply to create an electrode potential therebetween. 
     
     
       8. The apparatus of  claim 1  wherein the power supply is a DC power supply having a positive terminal coupled to one of the first and second electrodes and a negative terminal coupled to the other of the first and second electrodes. 
     
     
       9. The apparatus of  claim 1  comprising more than one pair of first and second permeable electrodes disposed in series in the flow of ground water containing contaminants and means for providing a potential between at least one of the permeable electrode pairs that differs from a potential between another of the permeable electrode pairs. 
     
     
       10. The method of  claim 1  wherein the electrical potential between said first and second permeable electrodes is between 10-40 volts. 
     
     
       11. An apparatus for treating an in situ flow of ground water containing contaminants, the apparatus comprising: 
       first and second permeable, planar metal electrodes; and  
       a DC power supply having a positive terminal coupled to one of the first and second electrodes and a negative terminal coupled to the other of the first and second electrodes to create a select potential therebetween;  
       the fist and second electrodes being disposed in situ in the flow of ground water containing contaminants with the fist electrode upstream from the second electrode and the water containing contaminants flowing through and between the electrodes, the electrodes being spaced a select distance whereby oxidation of the contaminates occurs in the vicinity of the positive electrode and reduction of the contaminants occurs in the vicinity of the negative electrode; wherein said flow of water is equal to a rate of flow of groundwater.  
     
     
       12. The apparatus of  claim 11  wherein the select distance is between about 0.001 and 1 meter. 
     
     
       13. The apparatus of  claim 12  further comprising a non-conductive spacer between the electrodes to maintain the select distance. 
     
     
       14. The apparatus of  claim 11  wherein the electrodes are made of a conductive material selected from the group consisting of stainless steel, aluminum, copper, platinized titanium, mixed metal oxides, gold and gold plated stainless steel. 
     
     
       15. The apparatus of  claim 14  wherein the electrodes are in a form selected from the group consisting of perforated plates, screens, wool, felt and weave. 
     
     
       16. The method of  claim 14  wherein the electrical potential between said first and second permeable electrodes is between 10-40 volts. 
     
     
       17. The apparatus of  claim 11  wherein the power supply is a DC power supply having a positive terminal coupled to one of the first and second electrodes and a negative terminal coupled to the other of the first and second electrodes. 
     
     
       18. A method of treating in situ ground water containing contaminants comprising: 
       providing in situ a pair of first and second permeable metal electrodes;  
       flowing the ground water containing contaminants through and between the electrodes at a flow rate equal to a flow of the groundwater; and  
       applying a voltage between each permeable electrode of the pair sufficient to promote oxidation of the contaminants in the vicinity of one electrode and reduction of the contaminants in the vicinity of the other electrode.  
     
     
       19. The method of  claim 18  wherein the contaminant is a halogenated hydrocarbon. 
     
     
       20. The method of  claim 19  further comprising periodically alternating the polarity of the electrodes. 
     
     
       21. The method of  claim 18  further comprising the electrodes being substantially planar plates disposed in parallel and substantially normal to the direction of flow of the ground water containing contaminants. 
     
     
       22. The method of  claim 18  further comprising providing more than one pair of first and second permeable electrodes. 
     
     
       23. The method of  claim 22  further comprising applying a voltage to at least one pair of permeable electrodes that is different from a voltage applied to another pair of permeable electrodes. 
     
     
       24. The method of  claim 18  wherein the voltage applied between said first and second permeable electrodes is between 10-40 volts.